1. Field of the Invention
The present invention relates generally to plumber's tools adapted for cleaning and removing obstructions from drain pipes and using an elongated member in the form of a coiled spring wire, known as a plumber's snake, which is advanced through the pipe and rotated. More particularly the invention relates to an improved snake feed device for use in connection with a plumber's tool embodying power means for rotating the snake.
2. Discussion of the Prior Art
Spring-type plumber's snakes are ordinarily housed in a drum or container having a conoidal wall through which the spring or snake is fed and retracted axially of itself as the container is rotated to cause rotation of the spring. In conventional tools having power-operated spring advancing and retracting means, the feed mechanism typically includes a jaw in the form of a segmented nut, or the like, through which the spring is fed by rotating it so that, in effect, the spring is threaded through the jaw. Since the jaw is stationary, the rate of feed of the spring or snake is entirely dependent upon its speed of rotation. Further, the stationary jaw cannot accomodate irregularities in the spring such as kinks, couplings and the like and if such irregularities are encountered, serious damage to the equipment can result. Also, should the spring or snake encounter a restriction within the pipe which it cannot immediately penetrate, the driving torque will build up against the stationary jaw causing the snake to kink and frequently break, thereby creating a significant safety hazard.
Various attempts have been made in the past to design a snake feed device which would permit the operator to quickly stop the feed should a blockage be encountered within the pipe. Among the most successful of these prior art devices are the devices invented by Hunt, et al., and described in U.S. Pat. Nos. 2,769,191, 3,224,024 and 3,499,782. These devices, while clearly superior to similar units on the market, nevertheless have the drawback that the feed jaws cannot accommodate any appreciable distortion in the spring and the feed of the spring is controlled entirely by the operator. Unless the operator is continuously alert to any indication of impedance to forward feed of the spring within the pipe, and quickly responds by stopping the feed, the buildup of driving torque can cause serious damage to the equipment and possibly injure the operator as well.
A highly successful device adapted to uniformly feed the coiled spring and to accomodate for distortion and irregularity therein is described in my earlier U.S. Pat. No. 3,882,565. The present invention comprises a simplified and improved version of the feed device described therein.
Certain types of prior art devices have attempted to feed the snake by using cooperating rollers set at an angle relative to the longitudinal axis of the snake. For example, by placing three roller wheels at a synchronized angle, a rotating spring can be urged forwardly. Such a system or arrangement, however, necessitates the exertion of significant downward pressure on the spring by the wheels. The exertion of too much pressure can "bind" the spring and too little pressure can cause undue slippage. In the present invention, helically grooved rollers are used and a minimum amount of pressure on the coiled spring by the rollers causes uniform feeding of the spring without binding or slippage.